Egge, J. University of Bergen, jorun.egge@ifm.uib.no

 
SEAWATER ENCLOSURE STUDIES ON THE NORWEGIAN COAST DURING THE LAST DECADE: I. INFLUENCE OF PHYSICAL, CHEMICAL AND BIOLGICAL FACTORS ON PHYTOPLANKTON DYNAMIC
 
Experiments with transparent seawater enclosures (volume 11-27 m3) lasting for about 1 month have been carried out yearly during the last decade. The enclosures have been filled with water containing natural plankton communities and supplied with nutrients (N, P and/or Si) of various compositions. Both the time of the year and the type of fertilization influence the species composition. In general, blooms of diatoms occur when silicate is supplied in addition to nitrate and phosphate, while blooms of species with no silicate demand, like Phaeocystis sp. and Emiliana huxleyi blooms occur when only nitrate and phosphate is added. Our gained knowledge of how to manipulate the phytoplankton community by fertilization manipulation, have made it possible to study the bloom dynamic of one certain species. Similarly it has enabled us to initiate blooms of different groups of plankton and then investigate effects of other parameters, like for instance turbulence or variable grazing pressure, on different plankton communities. The large volume of the enclosures also made it possible to investigate zooplankton dynamic and vertical flux.
 
Day: Thursday, Feb. 4
Time: 09:30 - 09:45am
Location: Eldorado Hotel
 
Code: SS51TH0930E